Take a look in Atmos ROM disassembly: http://www.defence-force.org/ftp/oric/d ... sembly.pdf
There are lot places marked with V1.0 and V1.1 which show differences in both versions - most are in page 2.
If the question is exactly for a zero page address then you can use $31 - Screen line width.
In Atmos ?PEEK(#31) returns always 40, in Oric-1 - 80 (or 93 if DOS is loaded) (which is actually BUG ).
BTW, this is used in SEDORIC too.

Take a look in Atmos ROM disassembly: http://www.defence-force.org/ftp/oric/d ... sembly.pdf
There are lot places marked with V1.0 and V1.1 which show differences in both versions - most are in page 2.
If the question is exactly for a zero page address then you can use $31 - Screen line width.
In Atmos ?PEEK(#31) returns always 40, in Oric-1 - 80 (or 93 if DOS is loaded) (which is actually BUG ).
BTW, this is used in SEDORIC too.